1. Relationship of Image Quality to Decision Accuracy for ARVC/D in MRI Elizabeth Krupinski, PhD Theron Ovitt, MD University of Arizona

2. ARVC/D Arrhythmogenic right ventricular cardiomyopathy / dysplasia RV muscle replaced by fatty &/or fibrous tissue Progressive  arrhythmic death

3. ARVC/D Most common  15 – 40 Premature ventricular beats Ventricular tachycardia left bundle branch block morphology Sudden cardiac death uncommon but may be 1 st sign Familial 30 – 50% cases

4. Use of MRI Differential diagnosis - RV outflow tract tachycardia (RVOT) Characterizes fat in free wall by  signal intensity Shows contraction abnormalities of RV

5. Rationale Acquisition protocols vary Image quality not studied Artifacts not studied Reader performance not studied

6. Cases 45 static MRI films – ARVC/D registry UofA – 7 met Task Force criteria – 31 suspected clinical signs – 7 imaged other reasons

7. Readers 12 experienced cardiac MRI radiologists 1 cardiologist expertise in MRI 13 different institutions US, Canada, Europe

8. Reading Protocol Cases  randomly 4 groups Mailed independently ~ 1 month between mailings Pre-formatted response sheet 6 clinical questions 3 image quality questions

9. Image Quality Rating Task Force Suspect ARVC/D No ARVC/D Excellent 7% 8% Good 37% 38% 45% Fair 44% 42% 38% Poor 12% 13% 9%

10. Motion Artifacts Rating Task Force Suspect ARVC/D No ARVC/D None 22% 16% 15% Mild 54% 43% 32% Moderate 22% 32% 45% Severe 9% 8% 2%

11. Other Artifacts Rating Task Force Suspect ARVC/D No ARVC/D None 52% 53% 65% Mild 13% 17% 25% Moderate 30% 22% 9% Severe 5% 8% 1%

12. IQ & Motion Artifacts Inverse relationship – No  mild = good  excellent – Moderate  severe = fair  poor X 2 = 159.413, df = 9, p < 0.0001

13. IQ & Other Artifacts Inverse relationship – No  mild = good  excellent – Moderate  severe = fair  poor X 2 = 135.82, df = 9, p < 0.0001

14. ARVC/D Decisions ARVD Present ARVD Absent Task Force 47% 53% Suspected 39% 61% No ARVC/D 29% 71% X 2 = 6.756, df = 2, p = 0.034

15. Decisions x IQ PoorFairGoodExcel TP 8% 43% 42% 7% FN 16% 42% 35% 7% FP 8% 42% 46% 4% TN 10% 35% 45% 10% X 2 = 11.74 df = 9 p = 0.2281

16. Reader Agreement 1/45 (2%) complete agree – No ARVD – All agree absent Kappa = 0.052 – Very low – Poor discriminability

17. Other Indicators If present =>  ARVC/D present – Fat in myocardium – Enlarged RV chamber size – RV configuration abnormal

18. Other Indicators No relationship with ARVC/D present – LV chamber size – Myocardium fat location Anterior wall RV OT RV apex

19. Conclusions Inter-observer variability high ARVC/D absent > present Task Force = Suspected Certain signs  probability ARVC/D reported present but inconsistent

20. Conclusions No established imaging protocol – Reduces IQ – Optimal views? – Motion & other artifacts Different MRI equipment Lack cine for wall motion abnormalities